Plural temperature refrigerators



E. w. ZEARFOSS, JR 2,794,324

PLURAL TEMPERATURE REFRIGERATORS June 4, 1957 2 Sheets-Sheet 1 Filed on. e, 1953 INVENTOR. Elf/76E w. ZEfiRI-OSS', J72

7 June 4, 1957 Filed Oct. 6, 1953 E. w. ZEARFOSS, JR 2,794,324

PLURAL TEMPERATURE REFRIGERATORS 2 Sheets-Sheet 2 I 1 I I 1 R4007 ram/a PF) i v INVENTOR.

51mm w. Zak/ '05; Jfi

United Sttes 2,794,324 PLURAL TEMPERATURE REFREGERATORS Elmer W. Zearfoss, In, Philadelphia, Pa., assignor to Philco Corporation, Philadelphia, Pa, a corporation of Pennsylvania Application October 6, 1953, Serial No. 384,467 14 Claims. (Cl. 62--8) tion may to advantage be embodied in refrigerators of.

the kind which include separate compartments each provided with evaporator means adapted to maintain the associated compartment within a predetermined temperature range. In this latter aspect, and with more particularity, the invention contemplates effecting controlled distribution of liquid refrigerant between two evaporator meansand consequent maintenance of desired temperatures-automatically, and in accordance with changes in ambient temperature.

It is now common practice to provide refrigerators having separate compartments within a single cabinet, for example separate freezing and food storage compartments. Commonly each of these compartments is provided with evaporator means, and the apparatus includes suitable control means adapted to establish flow of refrigerant to both evaporators in series and, in accordance with temperature conditions prevailing in the system, to terminate flow of refrigerant to the first evaporator in the series circuit while continuing flow of refrigerant to the second evaporator. In certain machines of this type the flow of liquid refrigerant is controlled in such manner as to cause the first evaporator, usually the evaporator associated with the higher temperature food storage compartment, to cycle between a minimum temperature well below the freezing point of water and a maximum temperature sufliciently above freezing to permit melting and consequent removal of frost deposited upon said first evaporator.

Frequently refrigerators of this known type employ valve device operating in conjunction with relatively complicated thermo-sensitive switches to achieve the desired distribution of refrigerant within the system. A novel and advantageous refrigerator of this latter type is disclosed and claimed in the copending application of Malcolm G. Shoemaker, bearing Serial No. 296,995, filed July 3, 1952, now Patent No. 2,706,894, and assigned to the assignee of the present invention. Broadly, it is a primary objective of this invention to provide simpler and less expensive apparatus adapted to attain at least the major objectives achieved by the system of said copending disclosure.

In general it is an objective of my invention to provide a novel method of and improved apparatus for effecting desired distribution of liquid refrigerant within a refrigerating system, automatically, and in response to ambient (room) temperature,

With more particularity my invention has as an objective the provision of truly automatic equipment in which distribution of liquid refrigerant is effected automatically in response to changes in ambient temperature and in a manner to maintain desired temperature conditions without the use of valves or complicated control circuitry.

" atent It is also an objective of this invention to limit the suction temperature, and therefore the loading, of a machine during pull-down periods.

In the method aspect, the invention contemplates utilizing the differences in refrigerant flow rate, which are occasioned by changes in ambient temperature, to produce controlled distribution of refrigerant as between two evaporators.

With special reference to the utility of the invention in the field of refrigerators of the plural compartment type, it is an object of my invention to modulate or control the supply of refrigerant to a pair of evaporators as a function of ambient temperature, and in such manner as to respond to the usage demands made upon the refrigerator, whereby the quantity of refrigerant delivered for example to the warmer compartment very closely approximates that which is required to obtain optimum refrigerating temperatures therein throughout a wide range of ambient temperatures, and without sacrifice of zerozone temperatures desired in the freezing compartment.

In achievement of the foregoing objects and advantages, and first briefly described, the apparatus of my invention includes novel refrigerant control means to which is delivered the refrigerant flowing from the restrictor and from which refrigerant flows to the evaporator, or evaporators, of the system. While the specific construction of this flow control means is dependent upon the type of use to which the apparatus is to be put, essentially it comprises a receptacle which receives refrigerant flowing from the restrictor and which has a pair of spaced outflow passages one of which leads to one path included 1 in the system and the other which leads to an alternative path, said receptacle being further provided with a re stricted passage disposed at a level below the level at which liquid and gaseous refrigerant enters, and through which restricted passage liquid refrigerant flows toward said outflow passages. The construction and arrangement is such that a head of liquid refrigerant is developed within said receptacle during operation of the system and, as will become clear as the description proceeds, the magnitude of this head is dependent upon the rate at which refrigerant is flowing in the system, that is upon the rate at which it flows into the receptacle, and upon the size of the mentioned restricted passage. The rate of flow in the system is of course a function of ambient temperature.

The head of liquid results in discharge of a jet or stream of liquid refrigerant through said restricted passage and toward said outflow passages. The ambient temperature prevailing under one condition of operation establishes a refrigerant flow rate such that said jet has a trajectory which reaches one of said outflow passages, and a predetermined change in ambient temperature establishing such a flow rate that said jet has a trajectory which reaches the other outflow passage. In this way the receptacle serves as means for modulating the flow of refrigerant between the alternative paths mentioned, and therefore for maintaining desired refrigerating temperatures over a relatively wide spread of ambient temperatures.

The manner in which the foregoing and other objects and advantages may best be achieved will be understood from a consideration of the following detailed description taken together with the accompanying drawings, in which two embodiments of the invention are illustrated.

In the drawings:

Figure 1 is a diagrammatic view of a plural evaporator refrigerating system incorporating apparatus in accordance with the invention;

Figure 2 shows modified apparatus embodying the invention; and,

Figure 3 is a graphical representation of refrigerating 3 capacity characteristic of a machine of the kind shown in Figure l, suction temperature being plotted as ordinates against ambient (room) temperature, as abscissae 7 Now making more detailed reference to the drawings, and initially to Figure 1 thereof, it is to be understood that the invention is therein illustrated diagrammatically as embodied in a refrigerator including .twoevaporators Hand 11 each of which is adapted to cool a separate zone or space, as is represented by dotted lines shown at 12 and 13. Preferably, although not necessarily, the space 12 constitutes the food storage compartment of a household refrigerator, whereas'the space '13 comprises thelow temperature freezing compartment of such a machine. It will be understood that the apparatus would be enclosed in a suitable insulated cabinet having partition means separating the aforesaid compartments.

In addition to the evaporators and 11 the system, in accordance with conventional. practice, includes refrigerant circulating means 14, which in the embodiment shown takes the form of a compressor, and a condenser 15 from'which liquid refrigerant flows toward the evaporators through expansion means of known type, for example through a capillary tube restrictor of the kind shown at 16. The restrictor delivers refrigerantto a suitable drier 17, from whence amixture of liquid refrigerant and flash gas is delivered to a modulating device or receptacle designated generally by reference numeral 18 and which device embodies the principal characteristic of my invention.

The modulator or receptacle preferably takes the form of a closed loop of tubing having a left-hand column or. portion 19, a right-hand column or and lower passes 21 and 22, respectively. A hydrostatic head of liquid represented at Ah is developed inthe left-hand column 19 during operation of the and this'liquid flows through a restricted port or passage 23 disposed in said column 19 at a level below the level at which refrigerant is delivered to the modulator. In passing through the port 23 the refrigerant forms a jet or stream which has, under different conditions, a trajectory of different lengths, as will be appreciated by a comparison of the jet shown in full lines, at 24, with the jet shown in dotted lines, at 25. The stream of shorter trajectory reaches an outflow passage 26 leading from the lower horizontal pass 24, whereas the stream of greater trajectory passes across the top of a small darn shown at 27 and reaches another outflow passage designated at 28.

From the passages 26 and 28 lead conduits 29 and 30,

conduit 29 being arranged to feed the evaporatorilO and conduit 30 being arranged to feed a by-pass conduit 31 through which refrigerant may flow directly to evaporator 11 without passing through evaporator '10. It will be understcodthat refrigerant delivered to evaporator 10 flows through both evaporators in series, passing from evaporator 10 to evaporator 11 through a connection 32, and returning to the compressor through suction line S. For a reason which will be referred to hereinafter, each of the conduits 29 and 30 is of slightly restrictive dimensions.

In operation, the modulating device 18 serves to distribute refrigerant between the two evaporators in such manner as to maintain desired temperatures within each of compartments 12 and 13, this result being accomplished automatically. in accordance with changes in ambient tempe'rature and without the use of valves; The manner inv which these results are achieved will now be described, with particular reference to the graphical representations of Figure '3. 7

As indicated above, liquid tends to build up in the left column 19 of device 18 and, as shown in Figure 1, flash gas flowing from the restrictor 16 is separated from the liquid, traversing horizontal pass 21 and flowing down the right column for delivery to the outflow passages 2 6 and 28 which supply the evaporators. For a given portion 20, and upper.

equipment ars-4,324 4 quantity of refrigerant delivered through the capillary tube (a quantity which was. equal for example to a flow rate of 10 lbs. of refrigerant per hour, in a system which yielded very satisfactory results) the liquid head Ah rises to a height dependent upon the mentioned flow rate and the restrictive eflect of the orifice or port 23 which forms the jet.

The apparatus is so designed that when refrigerant is flowing therein at 10 lbs. per hour the refrigerant discharged through the orifice 23 will have a trajectory such that it reaches a region near the top of the darn. If the flow rate is increased it will be understood that Ah is correspondingly increased, the trajectory becomes. longer, and the condition shown at 24,is attained, with the result that evaporator 10 is by-passed and all of the refrigerant flows to the upper, freezer evaporator 11. If, on the other hand, the flow rate be decreased Ah is correspondingly decreased, with the result that the trajectory becomes shorter, as shown at .25, and refrigerant flows through the outflow passage 26 and to the two evaporators in series. To appreciate the automatic modulation that is achieved by apparatus of this character, reference will now be had to Figure 3.

In considering Figure 3 it is to be understood that the capacity (flow rate) of a refrigerating system tends to-' ward a maximum at high suction and low ambient temperatures, and toward a minimum at low suction and high ambient temperatures. In the diagram suction temperature is plotted against room (ambient) temperature and the relation between the two temperatures may be determined at any point along the line showing aconstant flow rate of 10 lbs. per hour. The temperature control device 33, through the agency ofwhich cyclic though it will be operation of the compressor is effected, is so calibrated as to cause the freezer evaporator 11 to operate between predetermined suction temperatures ranging, by way of example, from about 0 F. to approximately 10? F., alnoted that the control device is associated with the evaporator 10 of the Warmer compart ment.

It is to be understood that since the bulb 33a of fcon-, trol device 33 is so disposed as to be affected by the tem-' perature of the air in the compartment 12, as well as by the temperature of the evaporator 10, the cut-off calibration temperature of the control device is somewhat above the 0 F. suction temperature hereinbefore mentioned. The cut-in calibration temperature of the device 33 is sufficiently above the freezing point of water to in-' surecomplete defrosting of the evaporator 10. It is to' be borne in mind that when the cut-in temperature of the control has been reached, the evaporator 10 having become completely defrosted, the freezer evaporator 11 has not risen substantially above 10? evaporator 11 is so proportioned with respect 'to the size of the compartment 13 as to permitrelatively little rise in the temperature of the latter evaporator dur-. ing even rather extended periods when the compressor is not in operation.

Now considering the low ambient temperaturecom. dition, that is the condition when little or no refrigeration is desired at the evaporator 10 which cools the warmer compartment, it will be seen by reference to point A that when operation of the compressor is initiated (the suction temperature having reached 10 F. and the control device having reached the higher cut-in temperature for which it is calibrated) the quantity of refrigerant delivered is greater than 10 'lbs. per hour. This is rep resented by the elevation of the 10 F. line above'the elevation of point A. It will be understood that the quantity delivered is in excess of IO lbspper hour because of the fact that the compressor is more efiicient at high suction temperatures.

Due to the increased flow rate the jet has therelativelylong trajectory shown at 24 in Figure 1, and refrigerant is accordingly delivered to the freezing evaporator 11 F. since the freezing only, traversing the path through the by-pass conduit 51. As is apparent from Figure 3, the refrigerating machine can maintain freezer evaporator suction temperatures in the range from 10 F. to F., in an ambient atmosphere maintained at 65 F., without causing the flow rate to drop materially below lbs. per hour. Under such a condition very little liquid refrigerant is fed to the lower evaporator 10, particularly because of the presence of the dam 27 which contributes to a sharp or clean cut-off of refrigerant as between the two outflow passages 26 and 28. Some cooling of the lower evaporator 10 is of course desirable at an ambient temperature of 65 F., in order that the device 33 may exercise control, and to accomplish this the cut-out suction temperature is, in practice, lowered a few degrees below the zero value plotted for exemplary purposes in Figure 3.

As described above, each of the conduits 29 and 30, which lead to the two evaporators, presents some restriction in the circuit. This restriction is present in order to overcome the hydrostatic differential which results from differences in elevation between the inlet regions of the two evaporators. To overcome such hydrostatic differential sufficient restriction must be introduced into the lines which feed the two evaporators to insure that enough pressure is developed in the modulator device 18 to overcome the aforesaid differential.

Considering now a high ambient temperature, for example ll0 F. (see point B), and bearing in mind that the evaporator system is cycling between 10 F. and 0 F., it will be seen that at such suction temperatures the flow rate is always less than 10 lbs. per hour (note Region of Double Evaporator Flow, which lies below the constant flow rate line), the jet has the shorter trajectory shown at 25, and refrigerant is fed to the two evaporators in series, through passage 26, during the entire operating period of the compressor.

If consideration is now given to operation at an ambient temperature of about 90 F. (point C) it will be seen that the flow rate varies from a value greater than 10 lbs. per hour to a value less than 10 lbs. per hour, as the evaporator suction temperature is lowered from 10 F. to 0 F. Accordingly under this condition the two evaporators are fed in series about half of the operating period of the compressor, whereas liquid refrigerant flows only to the upper evaporator during the other half of the operating period.

In brief, modulation as a function of ambient temperature is accomplished. By selection of cut-in and cut-out suction temperatures, by properly positioning the control bulb 33a, and by proper design and disposition of the component parts of the modulating device, the amount of refrigerant delivered to the lower evaporator which cools the compartment 12 can readily be made to approximate closely that which is required to maintain optimum refrigerating temperatures under any type of usage in the compartment, and throughout the entire range of ambient temperatures.

In tests of a representative system constructed in accordance with the invention, frozen food temperatures at the evaporator 11 varied: from 3 at 65 F.; to 25 at 80 F.; and back to 3 at 100 F. At the same ambient temperatures food stored within the lower compartment, and cooled by the evaporator 10, was maintained at 38.5", 395 and 39 F. at, respectively, the 65, 80 and 100 F. ambient temperature conditions. It is to be emphasized that this is very satisfactory, automatic performance.

As indicated in the statements of object appearing hereinabove, the invention also contemplates limitation of the suction temperature and therefore loading of a refrigerating system during the pull-down period. While this advantage is achieved in both embodiments, it can readily be understood by referring to the single evaporator embodiment of Figure 2. This embodiment-includes the usual compressor 14a, condenser 15a, and restrictor 16a,

and is provided with an evaporator shown at 11a. The outlet passages 26a and 28a of the modulating device are arranged in this embodiment to feed alternative restricted paths 35 and 36 each of which leads to the evaporator through a T connection 37. The path 36 includes a sump 38, which is preferably insulated as against heat exchange with the ambient atmosphere, and the path 35 has a portion 39 disposed in high heat exchange. relation with said sump.

In considering the operation of this embodiment, and with reference to the capability of the apparatus of the invention to limit the suction temperature of refrigerating machines generally, it is to be understood that when operation of a warm refrigerator is initiated the refrigerant fed to the evaporator evaporates at a relatively high rate. This elevated rate is in turn equivalent to a high suction temperature, with the result that the compressor is required to handle an abnormal quantity of refrigerant and is therefore overloaded, as compared with its normal loading. The embodiment of Figure 3 is particularly well adapted to utilize principles of my invention to limit this initial high loading.

When operation is started, the suction temperature tends to increase rapidly as described above. However the refrigerant, by virtue of the long trajectory which is achieved under high suction temperature conditions, is fed to the insulated sump 38 (note the longer trajectory jet 24a) wherein it is rapidly cooled with minimal evaporation of liquid in said sump. In this way elevation of the suction temperature under pull-down conditions is limited as compared with the suction temperature which would prevail if the liquid refrigerant were fed directly to a warm evaporator.

When the suction temperature decreases to a point such as to reduce the refrigerant flow rate sufficiently to cause the jet of refrigerant emitted from port 23a to reach its low trajectory condition, some of the liquid refrigerant available is fed directly to the evaporator through the alternative path 35. Due to the heat exchange relation between the sump and portion 39 of path 35, liquid refrigerant in the sump is gradually distilled therefrom and returned to the system through the evaporator 11a. Thus, and until the evaporator is pulled down to the desired operating temperature, the stream of refrigerant flowing through the port 23a has, alternately, a trajectory such that it feeds liquid to the sump and a trajectory such that liquid is fed to the path 35 and flows directly to the evaporator. When the evaporator has reached normal refrigerating temperature the trajectory is short and all of the flow is directly to the evaporator. During pulldown, however, a substantial portion of the refrigerant is delivered to the insulated sump, as a result of which the suction temperature, and therefore the loading, of the system is efiectively limited.

From the foregoing description it will be understood that by the present invention there is provided simple and inexpensive apparatus capable of effecting controlled distribution of liquid refrigerant between alternative paths in the system to maintain desired temperatures automatically, in accordance with changes in ambient temperature.

In the method aspect, the invention recognizes that use may be made of the differences in refrigerant flow rate occasioned by changes in ambient temperature, to produce a jet of varying trajectory and thereby to provide controlled distribution of refrigerant as between two evaporators.

The disclosed apparatus is of course subject to certain changes and modifications without departing from the essential spirit of the invention. For example expansion means other than the illustrated capillary type restrictor could be used; a high side float arrangement would be useful for the purpose. Additionally, the described modulating means could be used to by-pass the evaporator means completely. In such event provision would be made-(as by means of a suitablejauxiliary heat ex: changer) for re-evaporating the by-passed j liquid refrigerant prior to return thereoftothe compressorpump. However .it,will be understood that such changes and modifications are contemplated as come within the scope of the appended claims. fIclaimz 'a 1 7 1. In a refrigerating system of the type including'refrigerant circulatingmeans, expansion means, heat exchange means, and means defining apalir of'alternative flow paths interconnecting saidexpansion means and said heat exchange means, flow control apparatus effective to cause refrigerant'to flow toward said heat exchange means through one of said paths under one condition of M operation, and eflectiveto cause refrigerant toflow toward said heat exchange means through the other of said'paths' under another condition of operation, said flow control means comprising: a receptacle to which is delivered refrigerant flowing from said expansion means and having means providing a pair of spaced outflow passagesone of which leads to said one path and the other of which leads to said other path; said receptacle being provided with structure defining a restricted passage through which refrigerant may flow toward said outflow passages, the construction and arrangement being such that a head of liquid refiigerant is developed within said'receptacle during operation of the system, the body of liquid which comprises said head extending above and having its lower portion in communication with said restricted passage and the magnitude of said head and thereforethe pressure which said head exerts at said restricted passage being dependent upon the rate at which refrigerant enters said receptacle; said head resulting in discharge of a jet of liquid refrigerant through said restricted'passage and toward said outflow passages, under the said one'condition of operation said head being of such magnitude that said jet has a trajectory which reaches the outflow passage leading to said one path and, under the said other. condition of operation, said head being of such magnitude that said jet has a trajectory which reaches the outflow passage leading to the said other path.

-2.- A refrigerating system in accordance with claim 1, and further characterized in that said heat exchange means includes two portions, one of said paths being arranged to feed one portion directly, and the other of said paths being arranged to feed said two portions in series.

3. A refrigerating system in accordance with claim 1,

and further including wall structure so disposed between said outflow passages as to insure that liquid refrigerant delivered by said jet to either of said outflow passages is prevented from flowing to the other of said outflow passages.

4. A refrigerating system in accordance with claim 1, and further characterized in that one of said paths is provided with a sump portion and the other of said paths includes a portion arranged in high heat exchange relation with said sump portion.

5. A refrigerating system in accordance with claim 1, and further characterized in that one of said paths is provided with a sump portion insulated against heat exchange with the ambient atmosphere, and the other of said paths includes a portion disposed for heat exchange with said sump portion.

6. A refrigerating system in accordance with claim 1, and further characterized in that said receptacle includes: a column portion to an upper part of which said expansion means delivers refrigerant, and toward the lower end of which is disposed said restricted passage; a laterally projectingportionconfronting said restricted passage and from which lead said outflow passages; and means-for conducting'gaseous refrigerant from the upper part of :said column portion to said laterally projecting portion. 7 1 a 7 utlizing variations in pressure developed by said varying 1 7. In a refrigerating system ofthe type'includingrefrigerant circulating means, expansion means, andfirst and second evaporatorportions, andin which system, under oneicondition of operation, flow; of refrigerant is from said expansion meansjghrough said firstand second evaporatorportionsin series and thenceback to the cir culatingmeansp control means responsive to the rate of flow of refligerjant' within said system andeflective to cause refrigerant-to by-pass said first evaporator portion and to fiow directly to said second evaporator portion under a modified condition of operation, said control means comprising; a receptacle to which is .delivered re frigerant flowing from'said expansion means and having means providing a pair of spaced outflow passages one of which 'leads'th rough both said evaporator portions "and the other of which leads directly to said'second evapora= tor portion; said receptacle being provided with structure defining a restricted passage through which refrigerant may flow toward said outflow passages, the construction and arrangement being such that a head of liquid refrigerant is developed within said receptacle during operation of the system, the'body of liquid which comprises said head extending above and having its'lower portion in communication with said restricted passage. and the magnitude of said head and therefore the pressure which said head exerts at said restricted passage being dependent upon the rate at which refrigerant flows into said receptacle; said head resulting in discharge of a jet of liquid refrigerant through said restricted passage and to-. ward said outflow passages, the refrigerant flow rate under the said one condition of operation establishing a head which subjects said restricted passage to pressine in an amount such as to cause said jet to have a trajectory which reaches the outflow passage leading tosaid two evaporator portions, and the refrigerant flow rate under the said other condition of operation establishing a head which subjects said restricted passage to pressure in an amount such as to cause said jet to have .a trajectory which reaches the outflow passage. leading directly to said second evaporator portion.

8. A refrigerating system in accordance with claim 7, and further characterized in that the flow rate of refrigerant within the system varies as a function of ambient temperature, and in which system said expansion means delivers to said receptacle a mixture of liquid and gaseous refrigerant, the receptacle further including a portion extending above said head and providing for separation of the gaseous refrigerant from the liquid refrigerant developed within said head, and said receptacle also including a passage through which gaseous refrigerant passes toward said outflow passages.

9. In a refrigerating system of the type including refrigerant circulating means, expansion means, heat exchange means and means defining paths leading from said expansion means to said heat exchange means, the method of operation which comprises: developing a varying, hydrostatic head of liquid refrigerant within the system, the height of said head being a function of the rate of flow, which in turn is a function of ambient temperature; and utilizing pressure variations resulting from said varying head to control the distribution of said liquid refrigerant to said paths.

10. In a refrigerating system of the type including refrigerant circulating means, expansion means, evaporator means and meansv defining paths leading from said expansion means to said evaporator means, the method of operation which comprises: developing a varying, hydrostatic head of liquid refrigerant within the system, the height of saidhead being a function of the rate of flow, which is in turn a function of ambient temperature; and

head to control the distribution of said liquid refrigerant to said paths. 7

11. Ina refrigerating system of the type including 1'67 fi-igerant circulating means, expansion means, a pair of evaporator portions, and means defining one flow path leading from said expansion means to said two evaporator portions in series and another flow path leading directly to one of said evaporator portions, the method of operation which comprises: developing a varying, hydrostatic head of liquid refrigerant within the system, the height of said head being a function of the rate of flow, which is in turn a function of ambient temperature, and utilizing variations in pressure developed by said head to control the distribution of said liquid refrigerant to one or the other of said paths.

12. In a refrigerating system including expansion means for feeding liquid refrigerant and means defining a pair of paths to be fed, selectively, from said expansion means, flow control means, comprising, a receptacle to which is delivered refrigerant flowing from said expansion means, said receptacle being provided with structure defining a restricted passage through which refrigerant may flow toward said paths, the construction and arrangement being such that a head of liquid refrigerant is developed within said receptacle above said restricted passage during operation of the system, the height of said head being dependent upon the rate at which refrigerant enters said receptacle and the lower portion of the body of liquid which comprises said head being in free communication with said restricted passage, said head resulting in discharge of a jet of liquid refrigerant through said restricted passage and toward said paths and the height of said head determining the length of said jet, the construction and arrangement being such that refrigerant from said jet reaches one path in response to a relatively high flow rate in the system and reaches the other path in response to a relatively low flow rate in the system.

13. In a refrigerating system including expansion means adapted to feed liquid refrigerant, means defining a path to be fed from said expansion means and including an evaporator, means defining an alternative path to be fed from said expansion means and disposed to by-pass said evaporator, and means for feeding said two paths, selectively, including flow control means, comprising, a receptacle to which is delivered refrigerant flowing from said expansion means, said receptacle being provided with structure defining a restricted passage through which refrigerant may flow toward said paths, the construction and arrangement being such that a head of liquid refrigerant is developed within said receptacle above said restricted passage during operation of the system, the height of said head being dependent upon the rate at which refrigerant enters said receptacle and the lower portion of the body of liquid which comprises said head being in free communication with said restricted passage, said head resulting in discharge of a jet of liquid refrigerant through said restricted passage and toward said paths and the height of said head determining the length of said jet, the construction and arrangement being such that refrigerant from said jet reaches one path in response to a relatively high flow rate in the system and reaches the other path in response to a relatively low flow rate in the system.

14. In a refrigerating system of the type including refrigerant circulating means, expansion means, heat exchange means, and means defining a pair of alternative flow paths interconnecting said expansion means and said heat exchange means, flow control apparatus effective to cause refrigerant to flow toward said heat exchange means through one of said paths under one condition of operation, and etfective to cause refrigerant to flow toward said heat exchange means through the other of said paths under another condition of operation, said flow control apparatus comprising: refrigerant receiving means to which is delivered refrigerant flowing from said expansion means and having structure providing a pair of spaced outflow passages one of which leads to said one path and the other of which leads to said other path; and a restricted passage through which refrigerant flows toward said outflow passages, the construction and arrangement being such that a head of liquid refrigerant is developed within said refrigerant receiving means during operation of the system, the body of liquid which comprises said head extending above and having its lower portion in communication with said restricted passage and the magnitude of said head and therefore the pressure which said head exerts at said restricted passage being dependent upon the rate at which refrigerant enters said refrigerant receiving means, said head resulting in discharge of a jet of liquid refrigerant through said restricted passage and toward said outflow passages, under the said one condition of operation said head being of such magnitude that said jet has a trajectory which reaches the outflow passage leading to said one path and, under the said other condition of operation, said head being of such magnitude that said jet has a trajectory which reaches the outflow passage leading to the said other path.

References Cited in the file of this patent UNITED STATES PATENTS 2,402,802 Carter June 25, 1946 2,539,908 Jenkins Ian. 30, 1951 2,576,663 Atchison Nov. 27, 1951 2,604,761 Atchison July 29, 1952 2,622,407 Bixler Dec. 23, 1952 

